Association Between the Waist-Triglyceride Index and Incident Type 2 Diabetes in the Elderly: A Retrospective Cohort Study.

Introduction: Waist-triglyceride index (WTI) is a novel indicator of insulin resistance that can effectively identify glucose metabolism abnormalities and metabolic syndrome. No study discussed the predictive ability of WTI for incident Type 2 diabetes (T2D) risk from a longitudinal perspective. We aimed to evaluate the relationship between the baseline WTI level and the risk of T2D during follow-up in an elderly cohort. Methods: A total of 7578 participants aged over 60 years were enrolled in a follow-up study conducted from January 2018 to December 2023. The Cox proportional hazard models were performed to evaluate the independent effect of WTI level on T2D risk. The Kaplan-Meier method and restricted cubic spline (RCS) analysis were used to visually demonstrate the relationship between WTI and T2D risk. Receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) were employed to evaluate the efficacy of WTI and other composite lipid parameters in assessing the risk of T2D. Results: During a median follow-up of 3.91 years (interquartile range: 2.89-4.86 years), 758 participants (10.0%) developed T2D. Fully adjusted Cox proportional hazard models demonstrated a positive and independent association between WTI and T2D risk (HR = 1.57, 95% CI: 1.37-1.80, p < 0.001). The highest WTI group (Q4) exhibited the greatest cumulative incidence of T2D (log-rank test, p < 0.001). Additionally, the RCS analysis indicated that the relationship between WTI and T2D risk was linear. ROC analysis and DCA suggested that WTI performed better in the diagnosis and prediction of T2D risk. Subgroup analysis further validated the stability of these findings. Conclusion: According to our study, the elderly with an elevated WTI level were at a higher risk of incident T2D. WTI may serve as a promising novel biomarker for T2D in large-scale epidemiological studies.